Desorption and photopolymerization behavior of mixed and multilayered styrene-pyrrole nanofilms

The molecular arrangement and polymerization of adsorbed styrene-pyrrole films were explored using two different dosing schemes: simultaneous dosing to form an intimately mixed film of the two monomers and sequential dosing to form films with distinct layers of styrene and pyrrole. It was found that the desorption of pyrrole was delayed until 175 K when either simultaneously dosed with styrene or in the presence of an overlying styrene layer, whereas it normally desorbs at 165 K when dosed alone. No such effects were observed with styrene in any dosing configuration. The polymerization rate of pyrrole was unaffected in the films when present as the top layer and was observed to decrease by 50% when beneath a styrene layer. Moreover, the rate of polymerization increased by two orders of magnitude in the case of the intimately mixed film. The rate of styrene polymerization was not found to change in any of the explored geometries. These effects are explained by considering the proximity of the components and the potential for screening UV radiation based on their molecular structure.